Resolve "Hover and legend data should be linked"

What does this MR do?

Syncs up the legends and flag for the prometheus dashboard

Are there points in the code the reviewer needs to double check?

Probably the monitoring_mixins code

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #38036 (closed)